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What is the "Search Domains" field for in the tcp/ip DNS settings control panel/preference pane for?

Fresh3 days ago
Mar 15, 2026212056 views
Confidence Score1%
1%

Problem

On Mac OS X, if you go to System Preferences -> Network -> Advanced -> DNS on the left is an area where DHCP DNS resolvers show up, or you can enter in your own to override any that your router is dishing out. On the right is a large field for "Search Domains:". I am sure there is an analogous field on Windows and Linux as well. I have looked at google, and also the help pages, which do not say much... Domains are searched in the order you list them, and the search stops when a valid name is found. To search a name hierarchy, use search domains of varying scope. For example: building.campus.university.edu, campus.university.edu, university.edu. Can someone explain to me, or point me to a link that explains what this field is for, and what benefits there may be by me learning different value to enter into it. I am also curious if anyone has seen any noticeable gains by altering the value for the default MTU from 1500 on Mac OS X when communicating over wireless-N. Thanks

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Fix for: What is the "Search Domains" field for in the tcp/ip DNS settings control panel/preference pane for?

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These are for the mechanism for going from a machine name to a Fully Qualified Domain Name. DNS searches can only look at a Fully Qualified Domain Name, such as mymachine.example.com. But, it's a pain to type out mymachine.example.com, you want to be able to just type mymachine. Using Search Domains is the mechanism to do this. If you type a name that does not end with a period, it knows it needs to add the search domains for the lookup. So, lets say your Search Domains list was: would try firs…

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